Signal for lifting apparatus



Dec. 22, 1953 R. H. wlLLrAMs SIGNAL FOR LIFTING APPARATUS Filed Nov. 14,1949 INVENTOR RICHARD H. WILLIAMS BYH/Ck ATTORNEY Patented Dec. 22, 1953SIGNAL FOR LIFTIN G APPARATUS Richard H. Williams, Amsterdam, Ohio,assignor to National Delaware Steel Corporation, a corporation ofApplication November 14, 1949, Serial N0. 126,980

2 Claims. 1

The present invention relates to apparatus for lifting articles and isprimarily concerned with preventing the accidental dropping of thearticle or articles being lifted. The present inventon relates moreparticularly to improve ments in lifting cranes of the type used to liftladles of molten metal or to the lifting of other1 articles, thedropping of which would constitute a danger to the workmen and isprimarily concerned with the provision of means for signalling to thecrane operator when the crane hooks are properly in place for liftingthe ladle.

Relatively large overhead cranes are used in steel mills and otherplants for lifting and transporting iadles containing molten iron orsteel from one location to another location in the steel mill. Forexample, cranes are used to transport ladies of molten iron from themixer to thel open hearth furnace and to transport ladles of moltensteel from the open hearth furnace to the ingot molds. The molten metalmay be discharged from the ladle while the ladle is supported by thecrane or the 'crane may deposit the ladle on a suitable support. Thecrane customarily is' provided with a pair of depending hooks whichengage a pair of laterally extending trunnions mounted on the sides ofthe ladle. The crane operator, while located in a cab mounted on thecrane far above the mill door, lowers the crane hooks and moves theminto position to lift the ladle. When the hooks are in engagement withthe trunnions, the crane operator by "means of a suitable controlmechanism actuate's the crane to lift the ladle and to then move thecrane and the ladle to the new location. Giften, the ladle containinghot molten metal is lifted from the floor of the mill to a relativelygreat height. At times, the ladle of hot metal will slip from the cranehooks and fall to the mill floor scattering the molten metal over the'surrounding area. Such a ladle may contain, for example, 65 tons ofmolten .metal and may be lifted about 60 feet above the mill floor. Ifthe lifted ladle drops, the molten metal will severely burn anyone inthe immediate area, and the ladle and its contents will severely damageany equipment they may strike. While a ladle of molten metal is onlyinfrequently dropped. the lifted ladle does constitute a potentielhazard to the workmen.

4It is an object of the present invention to pre vent the raising orlifting of an. article when the raising or lifting apparatus and thearticle to be raised are not in lifting engagement with each other so asto preclude dropping of the article.

It is an object of the present invention to provide a lifting cranewhich includes a signal that automatically will indicate when the cranehooks are in correct lifting engagement with the ladle trunnions so thatthe crane operator will not operate the crane to lift the ladle when thehooks are not in the proper position and thereby prevent dropping of thelifted ladle.

In accordance With the present invention, the lifting apparatus isprovided with a signalling means which indicates when the article to belifted is properly engaged by the lifting appara tus so that theoperator will not lift the article when improperly engaged to preventdropping of the article. In a preferred embodiment of the presentinvention, a crane is provided With a signal light and means for turningon the light only when the lifting hooks are in correct liftingengagement with the ladle trunnions. This prevents the crane operatorfrom lifting the crane hooks and the ladle when the hooks are not infixed engagement with the trunnions. This prevents lifting of the ladlein such a manner that it can be subsequently dropped. The means forsignalling the operator may be readily and inexpensively installed toprevent the dropping of a ladle of molten metal with subsequent injuryto the workmen and equipment in the mill.

These and other objects and advantages will become more readily apparentwhen considering the following description, taken with the accompanyingdrawings, in which:

Figure 1 is a view in elevation of a crane lifting a ladle of hot metal;

Figure 2 is an enlarged fragmentary view in end elevation illustrating aportion of the crane and the ladle shown in Figure 1;

Figure 3 ls a side view in elevation of the apparatus shown in Figure 2;

Figure 4 is an enlarged, fragmentary sectional view taken along line4--4 of Figure 2, and

Figure 5 is a circuit diagram of the signaling apparatus provided by thepresent invention.

Referring to the drawings and more partici larly to Figure l, steelmills and other plants customarily have a relatively large overheadcrane l0 for moving a ladle l l of molten metal from one location toanother in the plane. Various types of cranes may be used. The crane leis one type customarily used and includes a main motor driven ycarriagel2 movable along rails i3 carried by posts it located at opposite sidesof the plant building. A second motor driven carriage I8 is mounted onrails ll carried by carriagelfZ. Thus, both carriages l2 and lil aremovable along rails i3, and carriage ifi is transversely movable alongrails l1. A bail i8 is suspended by cables I9 from 3 carriage I6, andthe bail I8 carries a pair of hooks 20, 2l adapted to engage a pair oftrunnions 23, 23 located on opposite sides of the ladle II.

In operation, the operator while located in an observation cab 25carried beneath carriage I2 actuates the controls located in the cab 25to move carriage I2 and carriage I8 to a position in which the bail I8is above the ladle to be lifted. A drum (not shown) on carriage I3 isthen caused to rotate to unwind the cables I8 and lower the bail I3. Thecrane and the bail are then maneuvered by the operator so that the hooks28, 2l engage the trunnions 23, 24 and then the ladle is lifted. Afterthe ladle has been lifted, the crane I8 is moved to transport the ladleII to a position above its new location, and the ladle is then lowered.All movements of the crane and the raising and lowering of the cranehooks is controlled by the crane operator located in cab 25 by means ofsuitable controls located in the cab.

The cab 25 is usually high above the mill floor and may, for example, beabout 60 feet above the point where the ladle is located. The ladle isquite large and contains a large quantity of molten metal; for example,the ladle may contain 65 tons of metal. At times, and after the ladlehas been raised, the ladle slips from the crane hooks and falls to themill floor. In addition to damaging the mill equipment, a failing ladleof molten metal obviously is dangerous to the Workmen.

As described above in detail, the crane IE and ladle I I are of the typecustomarily in use around mills and form no part of the presentinvention.

In accordance with the present invention, the lifting apparatus or cranewhich includes a member or hook adapted to be arranged in liftingengagement with the article or ladle to be lifted is provided with anelectrically operated signalling means for indicating tothe operatorwhen 4 to the bulb 21.

the lifting member is in lifting engagement with Y the article to belifted. Referring more particularly to Figures 2, 3 and 4, on the bailI8 which carries hooks 28, 2l there is mounted an electric light bulb 21protected by a transparent cover- Y ing 23. The bulb 21 is mounted in asocket 29.

A battery 3&3 is mounted on bail I8, and one side of thegbattery 38is'connected by an insulated wire 3i to one side ofy the socket and thebulb in the socket. The other side of 'socket 29 and bulb 21` isconnected through wire 32 to the conductive metal bail IB. In otherwords, the other side of the bulb is grounded. To the other side of thebattery 38, there is connected an insulated wire 33 that extends fromthe bail down through a protective conduit 34 mounted on hook 28 to post36. A second post 31 is mounted on the side of hook 20, and a bareconductive wire 38 extends between posts 31 and 36 and is connected towire 33. Each post insulates the wire 38 from the hook 2B. These postsare similar and only post'31 will be described in detail. Referring toFigure 4, post 31 comprises a stud 48 threaded into the side of hook 2tand a cylindrical insulator 4I formed of ceramic or other suitablematerial mounted on stud AG. The end of wire 38 is wrapped aroundinsulator 4I so that the wire is insulated from the hook 28. Theopposite end of wire 38 is similarly insulated from the hook 2l by post31.

Wire 38 is mounted on the hook in position so that it is engaged bytrunnion 23 only when the trunnion is positioned in the hook recess 42in the lower portion of the hook member 20. Preferably, the wire 38 isresiliently mounted so that it will give and not break when engaged bytrunnion 23. As shown, Va portion of wire 3B is coiled to form a spring44 so that when the trunnion engages the wire, the wire will stretch.The spring 44 may be a separate spring. When the trunnion and the hookare in lifting engagement, the trunnion, which is metal and conductive,electrically connects wire 38 and hook 28 to close the electric circuitto bulb 21 so that bulb 21 lights up only when the trunnion and hook arein lifting engagement with each other.

The wire 3l constitutes one side of an electric circuit, and the wire33, wire 38, hook 28, bail I8 and wire 32 constitute the other side of anormally open circuit for supplying electric current The wire 33 and thehook 20 which are insulated from each other in effect constitute meansfor closing the circuit only when the hook and trunnion are in liftingengagement with each other. If, for example, the end e3 of the hook 28engages the bottom of the trunnion so that the trunnion is balanced onthe end of the hook, then the fact that the light bulb does not lightwill indicate that the hook is not in proper engagement with thetrunnion and the operator will not actuate the crane to lift the ladle.The

crane operator in cab 25 is often so far from the ladle that it mayappear that hook 28 engages trunnion 23 when actually the hook `is notin lifting engagement with the trunnion. The signal light visuallyindicates when the hook is in lifting engagement, and the ladle will notbe lifted improperly and then dropped.'

A signal light bulb 41 and a battery i8 are electrically connected tohook 2i the .same as.4

described in connection with hook 28. v The bulb is connected by wire i8to battery 38 and.

grounded through wire 58 to the conductive metal bail IS. insulated wire5I to the exposed wire 52. Wire 52 is mounted on hook 2I in the samemanner as wire 38 is mounted on hook 23. When the hook 2| is in liftingengagement with trunnion 24, the trunnion 2li engages wire 52 and hook2I to close the circuit to bulb 3l. The wire 52 and hook 2I constitutean open switch that is closed only when the hook is in liftingengagement with the trunnion. A signal light is preferably provided foreach hook as it is possible to have one hook in lifting engagementwithout having the other hook being in lifting engagement.

A circuit diagram for either signal light is illustrated in Figure 5. Asshown, one terminal of the battery 30 is connected to a terminal of fthe light 21 through a lead 3l, while the other' terminal of the batteryand of the light are connected together through conductor 83, switch 6Iand conductor 32. The switch 5I includes terminals 63 and Sli and aswitching member 65 which is movable into contact with the terminals`rto form an electrical connection therebetween. The conductor 38corresponds to the wire 33, and

the switch contact 63 corresponds toA the wire 38. The other switchcontact 5d corresponds to the end 46 of the hook while the conductor 62represents the hook 28 and the bail I8. The switching member 65corresponds to the trunnion 24.

hooks properly engage the trunnions when the hooks do not.

Battery 139 is connected through I claim:

1. In a crane for lifting an article, the bination comprising, a liftinghook having a recess for receiving a portion of the article to be liftedwhen arranged in lifting engagement with an article to be lifted,electrically operated signal means, and a normally open electric circuitmeans for connecting the signal means to a source of electric current,said circuit means including a normally closed rst conductor means forconnecting one side of the signal means to a source of electric currentand a normally open second conductor means including the lifting hookfor connecting the signal means to the other side of a source ofelectric current. and said second conductor means including conductivemeans carried by the lifting hook in position to be engaged by saidportion and complete the electric circuit through the lifting hook tothe signal means only upon said portion of the article to be liftedbeing in the hook recess.

2. In a crane for lifting a ladle having a pair of electricallyconductive trunnions, the combination comprising, a bail, means forlifting the bail, a pair of hooks carried by the bail for engaging thepair of ladle trunnions, each hook having a recess for receiving thecorresponding trunnion when the hook is arranged in lifting engagementwith the trunnion, an electrically operated signal means carried by thebail for each hook, and an electric circuit for supplying electriccurrent to each signal means, each circuit including a rst conductormeans for connecting one of the signal means to one side of a source ofelectric current and a normally open second conductor means forconnecting the same signal means to the other side of the source ofelectric current, each of the second conductor means including one ofthe hooks and an exposed conductor member mounted on and insulated fromthe hook in position to be engaged by a trunnion upon the hook being inlifting engagement with the trunnion whereby the electric circuit foreach signal means is closed only upon a trunnion being positioned in therecess of the corresponding hook.

RICHARD H. WILLIAMS.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 327,919 Burmann Oct. 16, 1885 2,337,625 Walther Oct. 23, 19452,510,115 Jakosky June 6, 1950 OTHER REFERENCES American Merchant, pg.99, Feb. 3, 1944.

